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I need to do a latency test between two machines, basically a ping-pong packet test. I wonder what is the fastest connection I can have between those two machines. I imagine my options are:

  1. Ethernet through a router, but then my bottleneck will probably be the router unless you can recommend me a cheap and very fast router
  2. Ethernet through a switch, but then my bottleneck will probably be the switch unless you can recommend me a cheap and very fast switch
  3. Some kind of NIC-to-NIC connection using an ethernet cable
  4. Infiniband (that would be awesome but I don't think I will be able to do that at home due to its cost)
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closed as off topic by pauska, ewwhite, Sven, gWaldo, HopelessN00b Oct 30 '12 at 16:17

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2 Answers 2

up vote 2 down vote accepted

At home? Uhm....

Do not use extra hardware. No router, no switch. Just connect a Ethernet cable directly between the two NICs. And use the fastest Ethernet to minimise serialisation delays.

The reasons for this:

  • Extra hardware can only add delays. Use as few hops as possible.
  • It takes time for a datagram to be converter to a set electric signals on the line. Hence the fastest (Ethernet) link you can get.
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You mean use the fastest ethernet card available? What is the fastest one these days? –  chrisapotek Oct 30 '12 at 16:09
    
The card with the fastest wire speed. Affordable: 1Gbit (next to free). 10Gbit is about EUR 1000. And you would need two of these. –  Hennes Oct 30 '12 at 16:11
    
I am debating if I should do this over loopback and forget about wiretime for now since it will vary over 1Gbit, 10Gbit and Infiniband. Problem is: I will be sharing CPU power with 2 process, and I only have one quad-core chip. Maybe pinning each process to its own core will be enough but not sure. –  chrisapotek Oct 30 '12 at 16:14

Connect the two hosts with an Ethernet crossover cable.

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